Ken, a college entrance exam student, ends up living at the house of his aunt Shinjo, who lives in Tokyo. However, Shinjo seems to always go braless at home, and her large breasts and erect nipples are clearly visible even through her nightwear, making it impossible for Ken to focus on studying. Living with an aunt who unconsciously makes sexual advances, Ken's patience finally reaches its limit. Just then... 'Come on, touch my breasts?' Knowing that Ken is a virgin, Shinjo begins to seduce him, going beyond her role as his aunt.
